Light weight composites which have a good balance of high stiffness, high toughness, and low weight are used in many applications which require low flexibility and can benefit by reduced part weight. Transportation is one industry which has a need for such materials, for example, as a component of a vehicle or for an object (such as a container) which is being transported.
The ever present need to lighten the weight of transportation vehicles, as well as objects that are being transported, as well as the need for other lighter weight materials, and substitutes for conventional steel materials, has caused industry to investigate new composite materials, and particularly sandwich composite materials. Earlier applications filed by the present inventors have described such efforts in detail.
Unfortunately, the performance requirements imposed for many commercial applications generally create competing design tensions. A material meeting one need (e.g., stampability) may not necessarily meet another need, such as weldability. As such, until the work of the present inventors, materials able to meet the various needs in a commercially viable manner have yet to be employed. Efforts to employ sandwich composites similarly have been unsuccessful, with complications often arising from the inability to realize high integrity bonding among layers, as well as long term corrosion resistance. Of course, when adding in the need for stampability and weldability, many such materials have been ruled out as viable candidates. Accordingly, notwithstanding the many efforts in the art to date, until the work of present inventors, there has remained a need for an improved composite material, such as a sandwich composite material, which can be substituted for conventional steel materials without the need for significant investment in capital for those incorporating the materials into their finished products. There also has remained a need for a material that can be stamped. There also has remained a need for a material that can be welded, and especially welded using conventional welding techniques and/or equipment. There also has remained a need for a material that exhibits long term durability characteristics such as one of both of resistance to corrosion or resistance to delamination (e.g., resistance to delamination in ordinary service conditions, such as ordinary service conditions of automotive vehicle and can endure such conditions without delamination for extended period of time (e.g., 3, 5, 10, years or longer) of the layers of the composite. Further there remains a need for a polymeric-based composite mass that can be used alone or in combination with other materials, such as layered materials, which exhibits good processability, durability, electrical characteristics (e.g., charge dissipation characterisitics), or any combination thereof.
Also, there continues to exist a need for a weldable light weight composite having a polymeric layer having improved weldability (i.e., having a larger processing window for obtaining acceptable welds). Weldability may be measured by the weld current range (i.e., the difference between the maximum current that produces an acceptable weld and the minimum current that produces an acceptable weld, with other conditions such as weld pressure and weld time being kept constant, preferably at values that produce the best welds). Weldability may be measured by the weld time range (i.e., the difference between the maximum weld time that produces an acceptable weld and the minimum current that produces an acceptable weld, with the other conditions such as weld pressure and weld current kept constant, preferably at values that results in the best welds).